So-called Universal Integrated Circuit Cards (UICCs) are deployed in mobile phones, for example, and particularly, in mobile radio terminals corresponding to the GSM (GSM=Global System for Mobile Communication) or the UMTS (UMTS=Universal Mobile Telecommunication System) standard. Personal data of a mobile radio user, for example, are stored on such cards, wherein the integrity and the security of these data should be ensured. Typically, these cards store some hundred kilobytes, and experience has shown that the storage capacity will be expanded in the future.
Further, various applications may be stored on UICCs, such as the SIM application (SIM=Subscriber Identity Model), as used in GSM, or the USIM (USIM=Universal Subscriber Identity Module), as deployed in UMTS. A further application would be the ISIM (ISIM=IP Multimedia Services Identity Module), for example, such as may be deployed in IMS (IMS=IP Multimedia Subsystem). Various protocols are known in the conventional technique to read out data from such cards, which, for example, also permit to allow a communication between the card itself and a further interface, such as the CLF (CLF=Connection Less Front end).
One of these protocols is the SWP (SWP=Single Wire Protocol) known in the conventional technique. SWP enables communication in a master-slave scenario. In a case, for example, in which a master instance (e.g. a card reader) has “triggered” a data processing in the slave instance (e.g. a smart card), it may occur that after this “triggering”, at first no further data exchange takes place between the slave instance and the master instance until the data processing, e.g. a calculation, is completed and provides data for transmission to the slave instance. In this case it may occur, due to the particularities of the protocol used, e.g. SWP, that the master instance places the bus at the suspend state due to the lack of communication, which leads to the slave instance being “turned off” and the calculation being cancelled. In this case, the processing triggered is not completed and may have to be performed again, or leads to errors.
In the case of the SWP, the slave instance automatically changes into the idle state if no activity has been watched on the SWP bus for longer than 8 bits. This state may be a state without energy, for example, in which no further signal processing takes place. In this context, it may occur that the slave instance at this point of time is not yet ready to enter the idle state which, according to the example above, may have an unfavorable effect on the delays in the data transmission.